JP4084711B2 - Flexible optical disk and method for manufacturing flexible optical disk - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to prevention of damage to a flexible optical recording medium, particularly a flexible optical recording medium during recording and reproduction.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent No. 2924430 [Patent Document 2]
JP-A-6-60423 [Patent Document 3]
The optical disk is widely used as a CD or a DVD because it is replaceable and has a large storage capacity. In this optical disk, a recording film is usually formed on a polycarbonate disk substrate of 1.2 mm or 0.6 mm to record a signal indicating information, and the recorded information is reproduced. In order to collect the information recording / reproducing light on the recording surface, mechanical positional accuracy is required. For this reason, the disk substrate is flattened to have rigidity, and the optical pickup is servo-controlled to obtain position accuracy.
[0003]
In order to increase the recording capacity of the optical disk, the numerical aperture (NA) of the objective lens is increased, or the laser beam for recording / reproducing is shortened to further reduce the diameter of the light spot. In order to increase the numerical aperture of the objective lens, it is necessary to reduce the surface contact of the optical disk. For this reason, the focusing servo for improving the accuracy of the disk substrate and preventing the surface shake is mounted on the optical pickup, and a thin protective layer of about 0.1 mm is provided on the recording film, and recording / reproducing is performed from the protective layer side to prevent the surface shake. The margin has been expanded. Reducing the surface contact of the optical disk can be achieved by improving the material of the disk substrate and the manufacturing method, and increasing the precision of the focusing servo of the optical pickup, but this increases the cost. In addition, there is a method of reproducing directly from the recording film side without passing through the protective layer, but the distance between the surface of the recording film and the objective lens can be ensured only about 0.1 mm. In order to prevent this collision, it is necessary to improve the accuracy of chucking of the optical disk so as to reduce the surface vibration, which also increases the cost.
[0004]
Therefore, instead of forming the optical disk itself as a rigid body to increase the mechanical accuracy, a flexible optical disk is manufactured from a flexible material, and the flexible optical disk is rotated at a high speed so that it aerodynamically floats. The part facing the optical pickup is positioned and stabilized by a guide so that the surface touch is as close to zero as possible.
[0005]
As a method for producing this flexible optical disk, a thermoplastic sheet or a thermosetting resin is applied to the sheet surface while conveying a flexible sheet such as polyethylene terephthalate (PET) by a roll-to-roll method. Then, a heat press method in which a recording film is formed after the fine concavo-convex pattern of the stamper is transferred and thermally cured, or, for example, as shown in Patent Document 1, an ultraviolet curable resin is applied to the surface of a flexible sheet. A 2P method (Photo Polymerization method) in which a fine pattern of a stamper is transferred and UV-cured, and then a recording film is formed, or as shown in Patent Document 2, a flexible organic material sheet is heated to a softening point or more to obtain a stamper. After pressure bonding, there is a method of cooling and peeling the sheet and stamper.
[0006]
[Problems to be solved by the invention]
As described above, the guide is brought close to the base film surface on the opposite side of the transfer surface, and the surface vibration of the disc is reduced by the centrifugal force of the disc and the air flow between the guide and the disc. Although it is possible, the base film surface is soft and the base film surface is likely to be damaged if the guide transiently contacts the base film surface. Also, if the static electricity generated by the friction between the base film and the guide makes it easier to attract contamination or the base film is rubbed, and this rubbed or the like adheres to the recording / reproducing surface, the thickness of the base film becomes small. As a result, the recording / reproducing characteristics are deteriorated due to the deterioration of the surface deflection, and the error rate and jitter are likely to increase.
[0007]
In order to prevent these, for example, when an ultraviolet curable film of an oligoester acrylate-containing composition shown in Patent Document 3 is used as a protective layer on the guide surface side of the base film, the protective layer of such an ultraviolet curable film is Since the resistivity is about 10 ¹⁵ Ω, it is easy to be charged. When the protective layer on the guide surface side is charged, dust adheres to the surface of the protective layer, and the guide and the disk are completely in contact with each other. In some cases, the system system of the driver is damaged, and the driver suffers enormous damage.
[0008]
As a method of preventing the charging of the disk, a method of reducing the surface resistivity by forming a protective layer with a composition kneaded with a surfactant, or a method of forming an antistatic film on the surface of the protective layer is used. ing. However, a protective layer using a composition kneaded with a surfactant has a relatively high surface resistivity of about 10 ¹¹ to 10 ¹³ Ω, so that the antistatic effect is still insufficient. In addition, the method of forming an antistatic film on the surface of the protective layer requires two steps of forming a protective layer and forming an antistatic film, which is very disadvantageous in mass production and has a problem with durability of the antistatic effect. There is.
[0009]
In addition, the film serving as the film base of the flexible optical disc is industrially mass-produced, so that the thickness distribution is about ± 1 μm. In addition, since the recording film is on the order of nanometers, the order of thickness variations is almost negligible. It is the protective layer that requires the most strict management of the film thickness distribution. In the case of a surface recording type optical disc in which the preformat pattern surface of the optical disc comes on the pickup side and recording / reproduction is performed on that surface, the protective layer on the recording film side needs to function as an optical transmission film. In the conventional substrate transmission recording / reproducing optical disc, the protective layer has sufficient function as long as the protective layer is firmly adhered to the interface between the recording layer and the protective layer. It is essential that the interface is a smooth surface. For example, in the case of curing an ultraviolet curable resin that is a radical polymerization type, a plurality of materials are blended depending on the material that is configured, and there is a significant difference in the curing speed of each material. A material having a high curing rate cures immediately, but a material having a slow curing rate takes time to cure. Generally used oligomers and polyfunctional monomers form a crosslinked structure upon curing. Therefore, if a material having a high curing rate forms a crosslinked structure, the material that has been taken into the crosslinked structure by a material having a low curing rate is insufficiently cured and remains in a microgel state. This causes irregularities on the surface of the protective layer on the guide surface side of the base film, and the focus servo and residual focus error of the pickup become large, the servo is unstable and easy to come off, and the recording / reproduction characteristics are also poor.
[0010]
The present invention improves such disadvantages, has a smoothness layer, has a protective layer that can effectively prevent scratches on the base film and prevent charging, and further forms a smooth protective layer on the recording / reproducing side. It is an object of the present invention to provide a flexible optical disc capable of performing good recording and reproduction and a method for manufacturing the flexible optical disc.
[0011]
[Means for Solving the Problems]
The flexible optical disc of the present invention is a surface recording type flexible optical disc in which a recording film and a protective layer are laminated on a transfer surface of a base film to which a concave / convex fine pattern of a stamper is transferred, and a base opposite to the transfer surface of the base film is provided. A guide surface side protective layer containing conductive particles is provided on the surface of the film.
[0012]
The guide surface side protective layer is formed with a pencil hardness of H or higher to prevent damage to the base film.
[0013]
The guide surface side protective layer is formed of a cured layer obtained by irradiating a monomer material that does not take a crosslinked structure at the time of curing to enhance strength and smoothness.
[0014]
Furthermore, as the conductive particles contained in the guide surface side protective layer, one or more oxides of Sn, Sb, and In or carbon black or graphite are used, and are finely divided and uniformly distributed.
[0015]
Further, the content of the conductive particles in the guide surface side protective layer is made 10 to 60% by weight to uniformly disperse and to increase the antistatic effect.
[0016]
Moreover, the average particle diameter of the conductive particles in the guide surface side protective layer is uniformly dispersed within a range of 3 to 30 nm, and the smoothness of the guide surface side protective layer is enhanced.
[0017]
Furthermore, the thickness of the guide surface side protective layer is set in the range of 3 to 30 μm to form a durable uniform film.
[0018]
Further, the protective layer on the transfer surface side improves smoothness as a cured layer obtained by irradiating the monomer material that does not take a crosslinked structure at the time of curing with radiation.
[0019]
In the method of manufacturing a flexible optical disk according to the present invention, a recording film and a protective layer are laminated on a transfer surface of a base film onto which a concave / convex fine pattern of a stamper is transferred, and conductive particles are formed on a surface opposite to the transfer surface of the base film. A coating film of the composition for protective layer contained is formed, and the formed coating film is irradiated with radiation to be cured to form a guide surface side protective layer.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram of a flexible optical disk and a driver according to the present invention. As shown in the figure, the driver of the flexible optical disk 1 formed of a flexible material guides the opposite side of the flexible optical disk 1 to the objective lens 2 of the optical pickup that records and reproduces information on the flexible optical disk 1. 3, the flexible optical disk 1 is rotated aerodynamically by rotating at high speed with a spindle 4, and the portion of the floating flexible optical disk 1 facing the objective lens 2 is positioned and stabilized by the guide 3, thereby limiting the surface contact. It is close to zero.
[0021]
As shown in the schematic cross-sectional view of FIG. 2, the flexible optical disc 1 has a recording film 7 and a protective layer 8 sequentially laminated on a transfer surface 6 onto which a preformat pattern is transferred by a stamper of the base film 5. A guide surface side protective layer 9 is provided on the side opposite to the surface 6. The base film 5 is made of a resin film such as an acrylic resin, a polycarbonate resin, an epoxy resin, a polyolefin resin, a polyester resin, or a polyimide resin. The thickness of the base film 5 is usually about 0.05 to 1 mm, and the outer shape is selected according to the disc shape or other purposes.
[0022]
The guide surface side protective layer 9 is formed of a protective layer composition containing conductive particles in order to prevent damage to the base film 5 and enhance the antistatic effect. The protective layer composition for forming the guide surface side protective layer 9 is preferably composed of an organic material, particularly a material obtained by radiation curing a radiation curable compound or a composition for polymerization thereof. Examples of such materials include acrylic double bonds such as acrylic acid and methacrylic acid having an unsaturated double bond that is sensitive to ionization energy and exhibiting radical polymerizability, or ester compounds thereof, such as diallyl phthalate. Mention may be made of monomers, oligomers, polymers and the like containing or introduced in the molecule a group capable of crosslinking or polymerizing by irradiation such as unsaturated double bonds such as allylic double bonds, maleic acid and maleic acid derivatives.
[0023]
The radiation curable monomer is preferably a compound having a molecular weight of less than 2000, and the oligomer is preferably having a molecular weight of 2000 to 10,000. Examples of these include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol dimethacrylate, and the like. As pentaerythritol tetraacrylate (methacrylate), pentaerythritol acrylate (methacrylate), trimethylolpropane triacrylate (methacrylate), trimethylolpropane diacrylate (methacrylate), urethane elastomer (Niporan 4040) acrylic modification, or these Products with functional groups such as COOH introduced, phenol ethylene oxide addition Acrylate (methacrylate) of the product, compounds having an acrylic group (methacrylic group) or ε-caprolactone-acrylic group on the pentaerythritol condensed ring, and special acrylates disclosed in Patent Document 3. Examples of the radiation curable oligomer include an oligoester acrylate and an acrylic modified product of urethane elastomer, or those obtained by introducing a functional group such as COOH into these.
[0024]
Furthermore, in addition to these compounds or in place of these compounds, radiation curable compounds obtained by radiation sensitive modification of thermoplastic resins may be used. Specific examples of this radiation curable resin include acrylic double bonds such as acrylic acid and methacrylic acid having unsaturated double bonds exhibiting radical polymerizability, or ester compounds thereof, and allyl series such as diallyl phthalate. It is a resin that contains or introduces in the molecule of a thermoplastic resin a group that crosslinks or polymerizes upon irradiation with radiation such as a double bond, an unsaturated bond such as maleic acid or a maleic acid derivative. Examples of the thermoplastic resin that can be modified into the radiation curable resin include a vinyl chloride copolymer, a saturated polyester resin, a polyvinyl alcohol resin, an epoxy resin, a phenoxy resin, and a fiber derivative.
[0025]
Other resins that can be used for radiation sensitive modification include polyfunctional polyester resins, polyether ester resins, polyvinyl pyrrolidone resins and derivatives (PVP olefin copolymers), polyamide resins, polyimide resins, phenol resins, spiroacetal resins, An acrylic resin containing at least one acrylic ester and methacrylic ester containing a hydroxyl group as a polymerization component is also effective.
[0026]
Since the above-mentioned polymerization composition is cured by irradiation with radiation, particularly ultraviolet irradiation, it is desirable that the polymerization composition contains a photopolymerization initiator. There is no restriction | limiting in particular as this photoinitiator, For example, what is necessary is just to select suitably from normal things, such as an acetophenone series, a benzoin series, a benzophenone series, and a thioxanthone series. Further, a plurality of compounds may be used in combination as a photopolymerization sensitizer. The content of the photopolymerization initiator in this polymerization composition is usually about 0.5 to 5% by weight.
[0027]
The conductive particles contained in the organic substance may be opaque particles such as carbon black and graphite in addition to transparent particles such as tin oxide, antimony oxide, antimony oxide doped tin oxide, and indium tin oxide. That is, since the base film 5 and the guide surface side protective layer 9 do not need optical characteristics, the conductive particles do not need to be transparent.
[0028]
The resistivity of the conductive particles in the bulk body is desirably 1 Ω · cm or less, particularly 10 ⁻² Ω · cm or less. This is because if the resistivity of the conductive particles in the bulk body exceeds 1 Ω · cm, the antistatic effect becomes insufficient. The lower limit of the resistivity is not particularly limited, but is usually about 10 ⁻⁶ Ω · cm. The average particle size of the conductive particles is 3 to 30 nm. When the average particle size of the conductive particles is less than 30 nm, it is difficult to disperse the conductive particles in the guide surface side protective layer 9 to be formed. When the average particle size exceeds 3 nm, the surface of the guide surface side protective layer 9 formed This is to prevent these phenomena because smoothness is deteriorated and recording and reproduction are hindered. The particle diameter of the conductive particles may be calculated from the projected area of the particles observed with a scanning electron microscope.
[0029]
The guide surface side protective layer 9 is formed so that the content of conductive particles is 10 to 60% by volume. The content of the conductive particles in the guide surface side protective layer 9 is such that, after the guide surface side protective layer 9 is formed, the cross section is observed with a scanning electron microscope of about 10,000 to 100,000 times. What is necessary is just to obtain | require as an area ratio in the area | region containing about 1000 pieces. This is because if the content of the chargeable particles is less than 10% by volume, the antistatic effect is insufficient and uniform dispersion at 60% by volume becomes difficult.
[0030]
The hardness of the guide surface side protective layer 9 containing such conductive particles is preferably 2H or more, particularly 3H or more in terms of pencil hardness at 25 ° C. (JIS K 5400). This is because it is difficult to prevent damage to the base film 5 if the hardness of the guide surface side protective layer 9 is less than 2H. Moreover, although there is no restriction | limiting in particular in the upper limit of the hardness of the guide surface side protective layer 9, Usually, pencil hardness is about 6H.
[0031]
Next, a method of forming the guide surface side protective layer 9 on the base film 5 will be described with reference to the process diagram of FIG.
[0032]
First, as shown in FIG. 3A, conductive particles are applied to the surface opposite to the transfer surface 6 of the base film 5 in which the recording film 7 and the protective layer 8 are laminated on the transfer surface 6 to which the preformat pattern is transferred. The coating film 10 of the composition for protective layers to contain is formed. The method for forming the coating film 10 is not particularly limited, and various known methods such as spinner coating, gravure coating, spray coating, and dipping may be used. The coating conditions for forming the coating film 10 may be appropriately determined in consideration of the viscosity of the polymerization composition, the thickness of the coating film 10 to be formed, and the like. After the coating film 10 is formed on the surface of the base film 5, the heating process shown in FIG. In this heating step, the heating temperature is about 60 to 90 ° C. Thereafter, as shown in FIG. 3 (c), the coating film 10 is irradiated with ultraviolet rays using a mercury lamp or the like to radically polymerize the protective layer composition to cure the coating film 10 to thereby guide the protective surface side protective layer 9. Form. The intensity of ultraviolet rays applied to the coating film 10 is usually about 50 mW / cm ² or more, and the irradiation amount may be about 500 to 2000 mJ / cm ² . Moreover, depending on the case, you may irradiate an ultraviolet-ray, without heating, and you may irradiate an electron beam etc. instead of an ultraviolet-ray. Further, the guide surface side protective layer 9 may be formed not only on the main surface of the flexible optical disc 1 but also on the outer peripheral side surface and the inner peripheral side surface.
[0033]
When the guide surface side protective layer 9 is formed, the thickness after curing is in the range of 3 to 30 μm. That is, when the thickness of the guide surface side protective layer 9 is less than 3 μm, it is difficult to form a uniform film, and the durability is insufficient. Further, if the thickness of the guide surface side protective layer 9 exceeds 30 μm, cracks are generated due to shrinkage during curing, and warpage is likely to occur in the manufactured flexible optical disk 1, so that these phenomena occur. This is to prevent it.
[0034]
The surface resistivity of the formed guide surface side protective layer 9 is desirably 10 ¹⁰ Ω or less, particularly 10 ⁹ Ω or less. This is because if the surface resistivity of the guide surface side protective layer 9 is less than 10 ¹⁰ Ω, the antistatic effect is insufficient. The lower limit of the surface resistivity is not particularly limited, but is usually about 10 ² Ω.
[0035]
【Example】
[Example 1] After a preformat pattern on a stamper is transferred to one surface of a base film 5 formed of a polycarbonate resin to form a transfer surface 6, a recording film 7 is formed of an SbTe phase change material. Nonylphenoxyethyl acrylate (viscosity 80 mPa · s), which is a monofunctional acrylate photopolymer material, is applied to the surface of the recording film 7 and then cured by irradiating with ultraviolet rays to form a protective layer 8 with good smoothness. On the surface opposite to the transfer surface 6 of the base film 5 on which the recording film 7 and the protective layer 8 are laminated, a composition in which the following conductive particles are dispersed in the polymerization composition shown below is applied by spinner coating. After the heating, the guide surface side protective layer 9 was formed by curing by irradiation with ultraviolet rays. The formed guide surface side protective layer 9 had an average thickness of 5 μm.
Polymerization composition oligoester acrylate; 50 parts by weight (molecular weight 5,000)
PMTPA; 50 parts by weight acetophenone photopolymerization initiator; 3 parts by weight conductive particle antimony oxide; mean particle size 10 nm, bulk resistivity 10 ⁻⁴ Ω · cm In this case, conductivity for 100 parts by weight of polymerization composition The content of the functional particles is equivalent to 500 parts by weight. The pencil hardness of the formed guide surface side protective layer 9 was 3H, and the content of conductive particles in the guide surface side protective layer 9 was about 50% by volume. Further, the surface resistivity measured by the surface resistivity measurement method shown in JISK6911 was 0.5 GΩ.
[0036]
As shown in FIG. 1, the flexible optical disk 1 having the guide surface side protective layer 9 is mounted on the spindle 4, the guide 3 is brought close to the guide surface side protective layer 9 side of the flexible optical disk 1, and the flexible optical disk 1 is attached. As a result of performing a recording / reproduction test after rotating at high speed with the spindle 4 and performing a recording / reproducing test, the jitter of 8% or less in the DVD standard is 7% and the PI error of 280 / 8ECC or less in the DVD standard is 150. / 8 ECC, and good recording / reproduction characteristics could be obtained.
[0037]
Example 2 A flexible optical disk 1 was manufactured in the same manner as in Example 1. At this time, the composition for polymerization of the guide surface side protective layer 9 was the same as in Example 1, and tin oxide was used as the conductive particles. The average particle diameter of the conductive particles was 15 nm, and the resistivity in the bulk body was 3 × 10 ⁻⁵ Ω · cm. Also in this case, the content of the conductive particles with respect to 100 parts by weight of the polymerization composition was 500 parts by weight. The pencil hardness of the formed guide surface side protective layer 9 was 2H, and the content of conductive particles in the guide surface side protective layer 9 was about 45% by volume. The surface resistivity was 2 GΩ. As a result of a recording / reproducing test of the flexible optical disc 1 having the guide surface side protective layer 9, jitter was 7.4%, PI error was 220 / 8ECC, and good recording / reproducing characteristics could be obtained. .
[0038]
[Example 3] The polymerization composition of the guide surface side protective layer 9 was the same as that of Example 1, and the guide surface side protective layer 9 was formed using indium oxide as the conductive particles. The average particle diameter of the conductive particles used at this time was 12 nm, and the resistivity in the bulk body was 10 ⁻⁵ Ω · cm. Also in this case, the content of the conductive particles with respect to 100 parts by weight of the polymerization composition was 500 parts by weight. The pencil hardness of the formed guide surface side protective layer 9 was 2H, the content of conductive particles in the guide surface side protective layer 9 was about 40% by volume, and the surface resistivity was 5 GΩ. As a result of conducting a recording / reproducing test of the flexible optical disk 1 having the guide surface side protective layer 9, the jitter was 7.8%, the PI error was 250 / 8ECC, and good recording / reproducing characteristics could be obtained. .
[0039]
Comparative Example The polymerization composition for the guide surface side protective layer was the same as in Example 1, and the guide surface side protective layer was formed without containing conductive particles. The formed guide surface side protective layer had a pencil hardness of H and a surface resistivity of 2 × 10 ⁶ GΩ. The guide surface side protective layer was easily charged, and the flexible optical disk having the guide surface side protective layer was left still, and contamination was observed. In addition, as a result of the recording / reproducing test, the jitter was 9.2%, the PI error was 400/8/8 ECC, and good recording / reproducing characteristics could not be obtained.
[0040]
【The invention's effect】
As described above, in the present invention, conductive particles are contained on the surface of the base film opposite to the transfer surface of the base film in which the recording film and the protective layer are laminated on the transfer surface on which the uneven pattern of the stamper is transferred. By providing a protective layer on the guide surface side and enhancing the strength and antistatic effect, when the disc surface deflection is stabilized, damage to the flexible optical disc and the occurrence of contamination are prevented, and good recording / reproduction characteristics Can be obtained.
[0041]
By forming the guide surface side protective layer with a pencil hardness of H or higher, it is possible to increase the strength of the base film and prevent damage.
[0042]
In addition, the guide surface side protective layer is formed of a cured layer obtained by irradiating with radiation to increase the strength and stably obtain a good recording / reproducing characteristic for a long period of time.
[0043]
Further, by using one or more oxides of Sn, Sb, In or carbon black or graphite as conductive particles contained in the guide surface side protective layer, the particles are finely divided and uniformly distributed. The prevention effect can be enhanced.
[0044]
Further, by setting the content of the conductive particles in the guide surface side protective layer to 10 to 60% by weight, the conductive particles can be uniformly dispersed and the antistatic effect can be enhanced.
[0045]
Further, by setting the average particle size of the conductive particles in the guide surface side protective layer in the range of 3 to 30 nm, the dispersibility of the chargeable particles can be increased and the smoothness of the guide surface side protective layer can be increased. Stable recording / reproducing characteristics can be obtained.
[0046]
Furthermore, by setting the thickness of the guide surface side protective layer in the range of 3 to 30 μm, a uniform film having durability can be formed, and stable recording / reproducing characteristics can be obtained for a long time.
[0047]
In addition, the protective layer on the transfer surface side is high quality by reducing the residual focus error by increasing the smoothness as a cured layer obtained by irradiating the monomer material that does not take a crosslinked structure at the time of curing. Recording / reproducing characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a flexible optical disk and a driver according to the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a flexible optical disc.
FIG. 3 is a process diagram showing a method for forming a guide surface side protective layer.
[Explanation of symbols]
1; flexible optical disk; 2; objective lens; 3; guide;
4; spindle, 5; base film, 6; transfer surface, 7; recording film,
8: Protective layer, 9: Guide surface side protective layer.

Claims (9)

In a surface recording type flexible optical disc in which a recording film and a protective layer are laminated on a transfer surface of a base film onto which a concave / convex micropattern of a stamper is transferred
A flexible optical disk, wherein a guide surface side protective layer containing conductive particles is provided on a surface of a base film opposite to a transfer surface of the base film. The flexible optical disk according to claim 1, wherein the guide surface side protective layer is formed with a pencil hardness of H or higher. The flexible optical disk according to claim 1, wherein the guide surface side protective layer is a cured layer obtained by irradiation with radiation. 4. The flexible optical disk according to claim 1, wherein the conductive particles contained in the guide surface side protective layer are one or more oxides of Sn, Sb, and In, carbon black, or graphite. 5. The flexible optical disk according to any one of claims 1 to 4, wherein the content of the conductive particles in the guide surface side protective layer is 10 to 60 wt%. The flexible optical disk according to claim 1, wherein the conductive particles in the guide surface side protective layer have an average particle diameter of 3 to 30 nm. The flexible optical disk according to claim 1, wherein the guide surface side protective layer has a thickness of 3 to 30 μm. The flexible optical disk according to claim 1, wherein the protective layer on the transfer surface side is a cured layer obtained by irradiation with radiation. A coating film of a composition for a protective layer, comprising a recording film and a protective layer laminated on the transfer surface of the base film onto which the concave / convex fine pattern of the stamper has been transferred, and containing conductive particles on the surface opposite to the transfer surface of the base film And a guide surface side protective layer is formed by irradiating the formed coating film with radiation to be cured.

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